No, the reason we don't write clearly anymore is the feminist language rapists, according to language nudnik David Gelernter.
Geoff Pullum debunks some of Gelernter's claims about the history of English usage on the Language Log.
Here's an irony that Pullum missed: In the third paragraph's opening sentence, while lamenting the loss of our ability to write clearly, Gelernter makes an error of style and writes a garden path sentence - one that the reader has to re-parse midway through because of poor drafting. The sentence reads:
Our ability to write and read good, clear English connects us to one another and to our common past.As you process the sentence, you stop at "good" and wonder: is the author making fun by using "good" as an adverb, the way less educated speakers of English often do? Then you realize that no, he in fact just wrote the sentence badly.
What is it about illinguistic people that compels them to make perfect asses of themselves in public by combining language ignorance with a militant posture? And why does the phenomenon so often seem to involve political reactionaries trying to draw a connection between some perceived decline in language and some perceived decline in social values?
EDIT: a billion monkeys has a good review of Gelernter's rant.